This invention relates to an electronic typewriter with a single detector switch, which detects if a lid over a printing mechanism of the typewriter is open or closed, and which also detects distinctively if a carriage of the typewriter is at an original position.
A prior art electronic typewriter is provided with two independent switches, one being a carriage original position detector switch on one side of the printing mechanism and the other being a lid open detector switch on the other side thereof for detecting if the lid of the printing mechanism is open. In such a prior art, provision is made to stop the movement of the carriage and the printing motion of a print head after detecting that the lid is open, enabling an operator to exchange a ribbon or a type wheel easily. Here, the original position of the carriage means a predetermined position such as a left extremity of the carriage's mechanical movement. By the detection of the original position, a standard exact position is given from which the print head on the carriage will start printing. The original position of the carriage is detected immediately after the electronic typewriter is turned on and also when the lid, which is once opened for the exchange of the ribbon or the type wheel, is closed again. In these cases, the carriage is moved toward the original position detector switch, and then the original position is set up at the position where the carriage is located when the carriage stimulates the original position detector switch. In such a case that the carriage is moved to the original position after the typewriter is turned on, the carriage is moved for a definite distance from the original position to a predetermined left margin position. On the other hand, in such a case that the carriage is moved to the original position after the opened lid is closed again, the carriage is returned to the memorized position where the carriage was located just before opening the lid. As a result, printing can be always started at a certain position immediately after the typewriter is turned on, and printing can be resumed at exactly the printing position following the previous one when the lid is opened and closed during printing. Thus, uniformly printed lines can be obtained. Such an electronic typewriter is known, for example, from Japanese published unexamined patent applications No. Sho. 59-124881 and No. Sho. 58-71185.
The prior art electronic typewriter, as described above, is provided with different switches for detecting opening and closing of the lid and for detecting the original position of the carriage. Accordingly, it increases the number of the parts, which raises the cost.